1. Field of the Invention
The present invention relates to nitride semiconductor light emitting devices and methods of fabricating nitride semiconductor laser devices.
2. Description of the Background Art
It is generally known that a semiconductor laser device having a cavity with a facet degraded is impaired in reliability. It is considered that a cavity has a facet degraded when a nonradiative recombination level exists and accordingly the facet excessively generates heat. A major cause of such level is that the cavity has a facet oxidized.
Accordingly Japanese Patent Laying-Open No. 09-162496 (Patent Document 1) discloses a method coating a facet of a cavity with a coating film formed of a nitride not excluding oxygen to prevent the cavity from having the facet oxidized. Furthermore, Japanese Patent Laying-Open No. 2002-237648 (Patent Document 2) discloses a method coating a facet of a cavity of a nitride semiconductor laser device with a coating film of dielectric material of the same nitride as the facet to reduce a nonradiative recombination level.
Thus coating a facet of a cavity with a coating film of nitride has conventionally been known. Among nitrides, aluminum nitride (AlN) is particularly chemically and thermally stable and is an insulator of good quality, and is also high thermal conductivity and significantly effectively dissipates heat. As such, it exhibits an excellent feature as a coating film coating a facet of a cavity of a semiconductor laser (see Japanese Patent Laying-Open No. 03-209895 (Patent Document 3) for example). A coating film which does not contain oxygen, however, is generally high in stress and considered to lead to degradation such as dark line for example.